[python-win32] Understanding "Access Denied" when calling win32process.TerminateProcess() from Run As Administrator prompt

[Tim Golden]

On 14/11/2013 02:01, Tony Cappellini wrote:
> Sorry for the delay in replying, had a few more important crises to solve.
> 
> To summarize, I have a program running under Windows XP, which launches
> a process
> via os.spawnv(). When the user wants to exit the program they press
> Ctrl-C. The program terminates the process via 
> win32process.TerminateProcess(). Everything is normal.
> 
> Running under Windows 7, (using the same version of Python), an
> exception is raised when
> win32process.TerminateProcess() is called. I know know the reason why
> 
> Yes Tim, you're right about this. The external process I was trying to
> terminate
> with win32process.TerminateProcess() has already been terminated (when
> running under Windows 7)

[...]

> The things I don't understand are:
> 
> 1. Under Windows XP, the Ctrl-C does not terminate the process, and
> win32process.TerminateProcess() must be called.
> 
> 2. Under Windows 7, Ctrl-C DOES terminate the process, and
> win32process.TerminateProcess()
> should not be called.
> 
> 3. How (and why) does the Ctrl-C get propagated to the process, and why
> does it terminate the process, when the process is running in a separate
> address space?

This is a quick answer to say: unfortunately, Ctrl-C propagation on
Windows within Python itself and between processes in general is a small
nightmare! This is only complicated by the fact that you're using the
CRT spawn which does things under-the-covers to attempt to simulate
Posix semantics -- making it harder to reason about without pretty much
stepping through the code.

Hopefully someone else has (a) more time right now and/or (b) more
knowledge at their fingertips to give you a better answer. If no-one
else comes back I'll try to dig up more information. Ultimately, though,
the answer might be: you'll just have to cope with it!

TJG